1. Field of the Invention
The present invention relates to bridge breaker for the powder or particle (hereinafter called as powder) discharging system from receiving hopper to outside directly or downstream equipment. This device is usually equipped at the bottom of hopper and used to break plugging of powder (hereinafter called as bridge) happened at cone part of hopper by rotating a blade with motor.
Vibrator or knocker equipped at cone part of hopper is known for breaking bridge. But vibration or shock sometimes can't solve bridge, because powder is packed by vibration or shock and make situation worse. And wall of hopper is damaged by repeated stress for long period of operation by force of vibrator or knocker. Furthermore, in case of knocker, big noise happened.
Air injection into hopper is another way for breaking bridge. But in case of small amount of air, bridge can't be solved, and in case of large amount of air, releasing air from hopper is difficult because air contains a lot of powder, and much cost is required for air consumption.
The present invention relates to bridge breaker can solve bridge certainly without problems of damage of hopper, noise and cost for injection air.
2. Description of the Related Art
With respect to bridge breaker, the device as shown in FIG. 1 is used conventionally.
In this figure, upper part of the device is connected with flange C of hopper A having cone B by bolts, and lower part of the device is connected with flange D of downstream equipment. The clearance between flange C and the device is sealed by packing E, and clearance between flange D and the device is sealed by packing F.
Casing 1 having upper flange 1a, lower flange 1b and gear box 1c is divided into an upper part and a lower part to enable assembling of inside parts, though a demarcation line of the upper part and lower part and connecting bolts are not shown in FIG. 1.
Inner ring 2 having flange 2h is enclosed by casing 1 and is rotatably connected with casing 1 by ball bearing 14 with bolts 15.
Blade 3 has an upper part 3a which is inclined in parallel to the surface of cone B, and a lower part 3b which is vertical. Lower part 3b is connected with inner ring 2 by bolts 3f. 
Packing 16 and 17 such as an oil seal or grand packing are provided between casing 1 and inner ring 2 at both the top and bottom parts to prevent powder from entering into the device.
Chain sprocket 18 is connected with flange 2h of inner ring 2 and ball bearing 14 by bolts 111.
Geared motor 112 is connected with gear box 1c by bolts, and output shaft 12a is inserted into gear box 1c. 
Chain sprocket 110 is fitted output shaft 12a of geared motor 112 by key and bolts.
Link chain 19 ties chain sprocket 18 and chain sprocket 110 to transfer rotating torque of geared motor 112 to inner ring 2.
The bridge of powder is broken by rotating of blade 3, even at a slow rotating speed such as 0.5-3 rpm.
However, there are problems as for the conventional bridge breaker. 1) The ball bearing 14 receives heavy axial force by gravity of powder, and deformation of the ball bearing 14 causes problems such as stopping of operation or early wearing of the ball bearing. So, housings of the ball bearing 14 should have enough sturdiness, or should be fitted to casing 1 with severe tolerance to utilize sturdiness of the casing 1 and inner ring 2.
However because of a large diameter such as over 200 mm, fabrication of the ball bearing 14, and machining of fitted parts between the ball bearing 14 and casing 1, and between the ball bearing 14 and inner ring 2 are difficult. So much cost and time are required for machining.
2) Packing 16, 17 receive severe abrasion and quick wearing because of existence of powder. Touching parts of packing 16, 17 are worn in a few month of operation, and powder enters into the inside of the device, and finally operation can't be continued.
3) Bolts 3f to fix blade 3 to inner ring 2 are loosened easily, and additional fastening of bolts 3f is impossible during operation. Once bolts 3f are released, bolts 3f cause problems such as contamination of powder and damage of downstream equipment.
Furthermore sometimes the screws of bolts 3f become stuck in screwed holes, and a lot of repair work is necessary.